The state certification cannot be shrugged off as just another disputed episode, nor can it be seen as the climactic end to the presidential election.

Florida's certification essentially established the Republican candidate as the leader at this point in the on-going, post-election period, as court challenges spill into the next few days or weeks. It gave Bush legal and political leverage, a public relations rallying point and a chance to take advantage of the prevailing weariness with the whole recounting process.

Bush seized the occasion to declare victory, launch his transition team and call for national unity.

''Once our elections are behind us, once our disagreements are expressed, we have a responsibility to honor our constitution and laws and come together to do the people's business,'' he said in a brief speech televised nationally.

Sunday's events put the onus of protracted legal wrangling on Democratic candidate Al Gore, who shows no signs of conceding. Thrown on the defensive, Gore reportedly plans to explain to the public today why he must still contest the count in the courts.

His running mate Joseph Lieberman gave a preliminary response just minutes after the certification was announced, saying Gore had ''no choice'' but to challenge the reported Florida returns.

'' It is in our nation's interest that the winner in Florida is truly the person who got the most votes,'' Lieberman said.

Certification brought advantages to Bush but not finality or, in the minds of many Democrats at least, a sense of legitimacy. That has prompted Gore supporters to struggle on.

''If either candidate were to be declared the victor and electoral votes awarded based on the status today, neither candidate would be legitimate,'' Sen. Bob Graham, D-Fla., said on Sunday in Tallahassee.

''We are now going through a frustrating period, a period of inconvenience and anxiety,'' Graham said, pleading for patience. ''But that is nothing compared to what this country would go through if we had an illegitimate president, or a president who had to live with the title of illegitimacy for his full term in his office.''

Many Republicans, already quite satisfied with their candidate's legitimacy, hope to seize the momentum created by the long-awaited certification to foster a sense of finality. Almost immediately after the certification, several high-profile Republicans called for closure and an end to legal wranglings. They are hoping certification will put pressure on Democrats to either abandon further challenges or suffer the brunt of the public's impatience.

''At some point, there must be closure,'' a smiling James Baker, former secretary of state, said on Bush's behalf. ''At some point, the law must prevail and the lawyers must go home. We have reached that point.''

Neutral observers said the contest is far from over, that court challenges over the next few days or weeks could alter the outcome. But they said the Florida certification clearly boosted Bush's credentials in the public mind.

''I'm assuming it will be a public-relations coup of sorts for Bush to get the certification,'' said Robert Huckshorn, former chairman of the Florida Elections Commission and now an administrator at Florida Atlantic University. ''People have gotten to the point where they don't care who wins, they just want to get it over with.

I sense most people think. 'This has gone too far, let's get it done.''

In the court of public opinion, Gore's advocates have made his case for continued recounts on the basis that he got a plurality of the popular vote nationwide and -- if you set aside the disputed Florida count -- holds the lead in electoral votes as well.

If the Florida recounts had brought in a tide of new votes for Gore, the public attitude could have shifted in favor of continued legal challenges. But as of late Sunday, the recounts still left Bush with a lead, though it had shrunk to minuscule 0.01 of a percentage point out of about 6 million votes cast.

This lead, however slim, combined with the state certification, have put Gore under pressure to concede or face a possible public backlash from moderate voters -- independent-minded and less-partisan Americans who are targeted by both political parties and tip the balance in most elections.

''What you've got with voters are three groups: the hard-core Republicans, who think that Al Gore is a bad loser; the hard-core Democrats, who think Al Gore got robbed; and the folks in the middle, who have every reason to worry about the mood under which the next president takes office,'' Stephen Craig, professor of political science at the University of Florida, said on Sunday.

''For a while, that segment in the middle said, 'Let's count the votes.' But not now. It's not so much that this segment of the public rejects the possibility that the count is inaccurate, they are just growing tired of the process. They are ready to see it resolved, one way or other, but resolved.

''Both sides are wrapped up in their cocoons and utterly tone-deaf to what the public wants. It's just that Bush appears to have the cards and Gore doesn't. That's where we're at.''

After campaigning hard for nearly two years, Gore clearly is not yet ready to fold his cards.

Momentum in the exceedingly close presidential race has shifted many times, both before and after the election. The inconclusive outcome, wavering results on election night and the partisan split in the country have made both candidates reluctant to give up the fight, step aside and hope for satisfaction in the future.

Rarely have defeated candidates regained their party's nomination and gone on to victory. The parade of losers over the years prompted the old saying that there are no second acts in American politics. Richard Nixon defied this rule, winning an extremely close election in 1968 after losing an even closer one in 1960. But Nixon's experience was exceptional.

''To me, the loser of this presidential race is the winner. I'm not sure I'd want to be president under these circumstances,'' observed Richard Semiatin, an expert on presidential elections at American University in Washington. ''But both candidates look at it as their only chance to win the presidency.''

''If your whole adult life is geared to winning the presidency, it's hard to let go,'' Semiatin said. ''This might be your one shot at the brass ring. It's like they are two pugilists still slugging it out after the referee rules the bout a draw.''

The image of a bloodied survivor seems fitting for whoever becomes president. All this partisan punching nearly three weeks after Election Day already has delayed the usual healing process.

Bush, if he finally prevails, would come to office not only with less than a plurality of votes nationwide but dogged by questions about the legitimacy of 2000 election results that are likely to be debated well into the future.

''I think it's over. It should be over. Maybe that's the important word 'should.' '' said Bob Crawford, a Democrat on the state board that certified the election. ''We have a winner and it's time we move on. The one thing I'm sure of is that both sides have enough legal talent to keep this tied up through Christmas, but there's one thing the lawyers can't do for us and one thing the courts can't do for us, and that's bring this country together again.''